How does a piano make sound, and why did it matter?

When a pianist presses a key, a mechanism called the action throws a felt-covered wooden hammer at the strings. The strings vibrate, a bridge passes the vibration to a soundboard, and the soundboard amplifies it into the air. When the key is released, a damper stops the string. The instrument was significant because, unlike the harpsichord, it let a player change volume from note to note simply by touching the keys harder or softer. [1] [2]

According to [abc.net.au](https://www.abc.net.au/listen/classic/read-and-watch/how-music-works/how-does-a-piano-work/11192076), three assemblies carry the force of the finger to the string: the key, the wippen and the hammer. The wippen assembly transfers the key's force to the hammer and throws it toward the string. Because the hammer is thrown, it is out of the pianist's control at the moment of impact. [3]

The Acoustics Today article by Nicholas Giordano says the hammer typically travels at about 1 to 4 metres per second, from the quietest to the loudest playing. It is released from the action just before it hits the string and rebounds afterward. The ABC notes that this rebound matters, since a hammer that stayed on the string would stop it from sounding. That was the principle of the clavichord, which is so quiet it can barely be heard. [2] [3]

The struck string sets the pitch. Whether a note is high or low depends on the string's length, tension and mass. In a modern piano, midrange and higher strings are steel about 1 mm across, while bass strings have a more complicated construction. Each string runs from a hitchpin at the back, over a bridge glued to the soundboard, to a tuning pin at the front that adjusts tension. The bridge transmits the string's force to the soundboard, which produces the sound of the instrument. [2]

Most notes use three strings vibrating together, which gives a richer tone; the ABC says a single string would sound rather nasal. Lower notes use two strings, and the lowest eight notes use a single copper wire. [3]

The harpsichord plucks strings with quills, and the strength of the pluck is nearly independent of how hard the key is pressed. The organ also could not vary loudness from note to note. Bartolomeo Cristofori, an Italian harpsichord maker, built an instrument in which hammers strike the strings, so that finger force controls volume. His early name for it, usually given as a harpsichord that plays soft and loud, was shortened to piano. [4] [5] [2]

The Metropolitan Museum's curator says Cristofori wanted a keyboard that could phrase like a singer or a violinist, and that later music from Mozart concertos to Scott Joplin and Thelonious Monk depended on it. Giordano says the control it offered was quickly exploited by composers such as Mozart in the shift from the baroque to the classical era, and that the action explains why the piano displaced the harpsichord as the most popular keyboard instrument. [4] [2]

The sources differ on timing. The ABC places the invention in Padua in 1700, while the Met describes its own Cristofori piano as built in Florence in 1720 and as the earliest surviving example from his workshop. These are not necessarily contradictory, since one refers to the invention and the other to a surviving instrument, but the search results do not settle the exact date of the first piano. [3] [4]